Glacial imprints of the Okanogan Lobe, southern margin of the Cordilleran Ice Sheet

Abstract

The glacial geomorphology of the Waterville Plateau (ca. 55 km 2 ) provides information on the dynamics of the Okanogan Lobe, southern sector of the Cordilleran Ice Sheet in north-central Washington. The Okanogan Lobe had a profound influence on the landscape. It diverted meltwater and floodwater along the ice front contributing to the Channeled Scabland features during the late Wisconsin (Fraser Glaciation). The glacial imprint may record surge behaviour of the former Okanogan Lobe based on a comparison with other glacial landsystems. Conditions that may have promoted instability include regional topographic constraints, ice marginal lakes and dynamics of the subglacial hydrological system, which probably included a subglacial reservoir. The ice-surface morphology and estimated driving stresses (17-26 kPa) implied from ice thickness and surface slope reconstructed in the terminal area also suggest fast basal flow characteristics. This work identifies the location of a fast flowing ice corridor and this probably affected the stability and mass balance of the south-central portion of the Cordilleran Ice Sheet. Evidence for fast ice flow is lacking in the main Okanogan River Valley, probably because it was destroyed during deglaciation by various glacial and fluvial processes. The only signature of fast ice flow left is the imprint on the Waterville Plateau.

Climate change and ecosystem response in the northern Columbia River basin — A paleoenvironmental perspective

“…In some places these lobes created huge ice dams disrupting the normal flow of the Columbia River and its tributaries (Clague 1989;Kovanen and Slaymaker 2004;Smith 2004). As the ice built, lobes of ice slowly inundated the valleys of the northern Columbia basin, eventually blanketing the highlands, and even high mountain peaks to form a Cordilleran ice sheet.…”

“…year BP, about 3500 years after the global glacial maximum (Booth 1987;Ryder et al 1991;Begét et al 1997;Kovanen and Slaymaker 2004), and then began to retreat northward into British Columbia. The glacial chronology in our study region is less well known.…”

“…The glacial chronology in our study region is less well known. years BP, but recent evidence (Atwater 1987;Begét et al 1997;Brunner et al 1999;Kovanen and Slaymaker 2004) suggests that these floods occurred, and the Purcell Trench Lobe had already begun to retreat, prior to ca. years BP, but recent evidence (Atwater 1987;Begét et al 1997;Brunner et al 1999;Kovanen and Slaymaker 2004) suggests that these floods occurred, and the Purcell Trench Lobe had already begun to retreat, prior to ca.…”

Development of the topography-controlled Upper Odra ice lobe (Scandinavian Ice Sheet) in the fore-mountain area of southern Poland during the Saalian glaciation

“…The most spectacular lobes existed along the southern margin of the Laurentide Ice Sheet (Clark, 1992;Patterson, 1997;Colgan, 1999;Mickelson and Colgan, 2003;Kehew et al, 2005;Jennings, 2006;Lusardi et al, 2011). However, lobes were also common along the margin of the Scandinavian Ice Sheet (Punkari, 1997;Boulton et al, 2001;Piotrowski et al, 2006;Wysota et al, 2009;Narloch et al, 2012Narloch et al, , 2013 and other large ice masses (Hicock and Lian, 1999;Kovanen and Slaymaker, 2004;Boulton and Hagdorn, 2006;Boston et al, 2010;Evans and Thomson, 2010).…”

Deglaciation of the North Cascade Range, Washington and British Columbia, from the Last Glacial Maximum to the Holocene

“…1). Wilson et al (1958), Prest et al (1968), Waitt (1972Waitt ( , 1977Waitt ( , 1979, Waitt and Thorson (1983), Booth (1986), Clague et al (1980Clague et al ( , 1983Clague et al ( , 1989, Ryder (1989), Kovanen and Slaymaker (2004), Riedel (2015), and Evans (written communication). Ice surface contour interval is 200 m.…”